If I'm reading my Govier book correctly, there were 1701 340 4-sp. BS23 'cuda's built. As far as Challengers go, no engine sizes were listed in my book, just a breakdown of 4-sp. Challengers and Challenger Rallyes. They broke down as follows :
JS23 Challenger Rallye 4-sp. - 1243
JH23 Challenger 4-sp. - 357
I've got an older Govier book, though, 1994 print date, maybe someone out there has a newer one that would show more complete information. Hope this helps!